I have read that the diesel tanks are open bottomed, because fuel is less dense than water, it floats. As the diesel is used up, sea water takes its place. Is this true ? I thought that water was the enemy of diesel engines .... i.e. if water got into them , that was the end of the engine. Surely with this method, water contamination would be a big issue. Grateful for any thoughts on this. Thanks. Pras